Application of Biochar in Potato Production and Its Effects on Soil Properties, Crop Yield, and Quality

Biochar is an organic amendment produced by a process called pyrolysis, which is the burning of biomass in a limited oxygen environment. This study investigated the effect of biochar in potato (Solanum tuberosum L.) production. The study comprised of a randomized complete-block design with following rates of biochar: 0, 6.2, 12.4, or 24.8 t/ha.  Each treatment plot was 81 m² and was replicated four times. Biochar was applied and disked in on 12 April, 2012. A mid-season chipping potato (cv. Atlantic) was seeded on April 12 and April 22 in 2012 and 2013, respectively. Herbicide and fertilizer applications were made later in the season based on Midwest Vegetable Production Guide. Potato was harvested on 26 July and 1 August in 2012 and 2013, respectively, and graded into marketable and non-marketable category. At the end of the growing season in 2012, soil pH ranged from 6.1 to 6.4 but there were no statistically significant differences. In 2013, soil pH increased with highest pH recorded in 24.8 t/ha biochar treatment. There was no effect of biochar on soil electrical conductivity. Plant height and canopy width was also not affected by biochar. There was a general trend of increased yields with increasing biochar rates but differences were not statistically significant. Similarly microbial biomass carbon also increased with higher application rates but did not show significant differences. The effect of biochar on vegetable crop yields are not widely available, however, row crop studies have shown yield reductions in the first couple of years of biochar use followed by increases in subsequent years. Increases in crop yields have been attributed to better water holding capacity, higher cation exchange capacity, increased nutrient retention, and the ability of biochar to reduce bulk density.  Since this study was conducted during the first two years after biochar application, it is early to speculate long-term effects of biochar on soil properties, crop growth, and yield. Biochar could be a valuable tool for management of soils that are either degraded or have poor nutrient status; however, it could take time to observe significant changes in soil and crop attributes after biochar addition.